EXTERNAL NEGATIVE PRESSURE DURING LISA

This pilot study evaluates the feasibility, safety, and preliminary effectiveness of applying external continuous negative pressure (ECNP) during less invasive surfactant administration (LISA) in preterm infants with respiratory distress syndrome (RDS) supported by non-invasive respiratory support. ECNP, delivered via a modern negative-pressure ventilation device and a soft thoracoabdominal cuirass, generates a sustained sub-atmospheric pressure around the chest wall. This mode of support is intended to facilitate spontaneous breathing, promote more homogeneous lung inflation, and potentially enhance the distribution of intratracheally delivered surfactant.

LISA using thin catheters is a widely adopted method for surfactant administration in spontaneously breathing neonates receiving CPAP or HFNC. Although effective, the procedure is frequently complicated by transient hypoxemia, bradycardia, apnea, and surfactant reflux, occasionally requiring temporary interruption or conversion to more invasive therapy. These complications may impair surfactant delivery, contribute to uneven lung aeration, and lead to the need for repeated dosing. To date, the integration of continuous negative-pressure support during LISA has not been evaluated in clinical practice.

In this single-arm feasibility study, ECNP will be initiated shortly before and maintained throughout the LISA procedure. The study will assess whether negative-pressure support stabilizes spontaneous ventilation, improves oxygenation, and facilitates more uniform surfactant distribution during administration. Safety will be evaluated based on the occurrence of serious procedure-related events requiring interruption, such as significant desaturation, bradycardia, or apnea requiring positive-pressure ventilation. Effectiveness will be explored through measures of post-procedure oxygenation stability, need for repeat surfactant dosing, and indicators of adequate surfactant distribution (e.g., imaging assessments when clinically indicated).

This exploratory study is designed to inform the potential utility of ECNP as an adjunct during LISA and to determine whether a larger controlled trial is warranted. The protocol focuses on documenting feasibility (ability to complete LISA under ECNP), characterizing physiologic responses, and capturing any adverse events specifically associated with ECNP use in this population

Inclusion criteria

• Preterm infants ≥ 32 weeks of gestational age
• FiO₂ > 0.30 for more than 30 minutes on CPAP (6 - 8 cm H₂O) or HFNC (8 l/min)
• Increased work of breathing despite FiO₂ < 0.30
• Birth weight > 800 g
• X-ray confirmed RDS
• Availability of all required devices and appropriately fitting cuirass

Exclusion criteria

• Requirement for endotracheal intubation or mechanical ventilation prior to surfactant administration
• Major congenital anomalies (cardiac, pulmonary, chromosomal)
• Known or suspected neuromuscular or metabolic disorders
• Lack or withdrawal of informed parental consent